Magnetic solid-phase extraction material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of magnetic solid-phase extraction, in particular to a magnetic solid-phase extraction material and a preparation method and application thereof. The preparation method of the magnetic solid-phase extraction material comprises the following steps: S1, dispersing Fe3O4 nanoparticles in an organic alkaline solvent, adding a silanization reagent, stirring, and washing to obtain Fe3O4 / SiO2 particles; and S2, dispersing the Fe3O4 / SiO2 particles and Uio-66-SO3H particles in an organic alkaline solvent, adding a silanization reagent, stirring, washing and drying to obtain the magnetic solid-phase extraction material. The magnetic solid-phase extraction material provided by the invention has a very good adsorption effect on seleno-amino acid in health-care products, target seleno-amino acid and a sample matrix can be quickly separated by adopting a magnetic solid-phase extraction method, and the magnetic solid-phase extraction material has the characteristics of high separation speed and simplicity in operation.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic solid phase extraction, and particularly relates to a magnetic solid phase extraction material, a preparation method thereof and an application thereof. Background Art

[0002] Selenoamino acids are a unique class of amino acids containing selenium element, which play important physiological roles in organisms. Selenium, as an essential trace element for the human body, can also participate in the synthesis of proteins in the form of selenoamino acids, not only endowing these proteins with unique structures and functions, but also greatly enhancing their antioxidant capacity and biological activity. Especially in aspects such as the antioxidant defense system, thyroid hormone metabolism and immune system regulation, selenoamino acids play an indispensable role. By introducing selenium element through natural selection or artificial synthesis, more and more new selenium-containing nutritional supplements and health foods with higher bioavailability and specific health benefits have been developed, and most of them exist in the form of selenoamino acids.

[0003] Selenoamino acids such as selenocystine (SeCys2), selenomethionine (SeMet), methylselenocysteine (MeSeCys), etc. have higher bioavailability and lower toxicity compared to inorganic selenium. A variety of agricultural products, such as grains like wheat, rice, soybeans, etc., are rich in selenomethionine (SeMet), and vegetables like onions, garlic, broccoli, mushrooms, etc. are rich in selenocystine (SeCys2), methylselenocysteine (MeSeCys), etc. Therefore, health foods made from these agricultural products can provide users with a variety of selenoamino acids. Although the intake of selenium is beneficial to the human body, the safety window of selenium is very narrow. The Chinese Nutrition Society recommends that the daily selenium intake for normal people is 60 - 200 μg, and selenium entering the human body exceeding this dose will cause poisoning. Therefore, establishing a simple, rapid, sensitive and accurate detection method for selenoamino acids in health foods is of great significance for clarifying the nutritional value of selenium-containing health foods and preventing their harms.

[0004] Coupled techniques such as liquid chromatography - inductively coupled plasma mass spectrometry (LC - ICP - MS), liquid chromatography - atomic fluorescence spectrometry, etc. have been proven to be effective means for the analysis of selenium species, especially selenoamino acids. Among them, LC - ICP - MS has the advantages of no need for derivatization, high sensitivity, wide linear range, etc., and is the most effective detection technology for selenoamino acid analysis. However, the raw materials of health food samples are diverse, the matrix is complex, and there are many interfering substances. These matrices will affect the accuracy and sensitivity of detection and cause misjudgment of the detection results. For selenoamino acids with relatively low concentrations, the detection sensitivity may also be insufficient. Therefore, sample pretreatment is required before LC - ICP - MS detection.

[0005] The sample is usually pretreated by magnetic solid-phase extraction. However, the existing magnetic solid-phase extraction materials have unsatisfactory extraction effects on selenoamino acids. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a magnetic solid-phase extraction material, its preparation method and application. The present invention synthesizes a magnetic solid-phase extraction material that has an adsorption effect on selenoamino acids. The target selenoamino acids can be rapidly separated from the sample matrix by magnetic solid-phase extraction, which is characterized by fast separation speed and simple operation. The extraction material is used for the extraction of selenoamino acids in health foods, and then combined with LC-ICP-MS detection technology to establish a highly sensitive, simple and stable extraction and detection method for selenoamino acids in health foods.

[0007] Therefore, the present invention provides the following technical solutions.

[0008] In a first aspect, the present invention provides a preparation method of a magnetic solid-phase extraction material in an optional embodiment, including the following steps:

[0009] S1: Dispersing Fe3O4 nanoparticles in an organic basic solvent, adding a silanization reagent, stirring and washing to obtain Fe3O4 / SiO2 particles;

[0010] S2: Dispersing the Fe3O4 / SiO2 particles and Uio-66-SO3H particles in an organic basic solvent, adding a silanization reagent, stirring, washing and drying to obtain a magnetic solid-phase extraction material.

[0011] Preferably, the mass ratio of the Fe3O4 / SiO2 particles to the Uio-66-SO3H particles is 1:1 - 1.5, preferably 1:1; and / or, the mass-volume ratio of the Fe3O4 nanoparticles to the silanizing reagent is 1 g:2 mL; and / or, the silanizing reagent includes one or a mixture of tetramethoxysilane or tetraethoxysilane. In step S1, the organic basic solvent includes an organic solvent, water, and a basic solvent, and the volume ratio of the organic solvent, water, and ammonia water is 100:12:7; the pH of the organic basic solvent is greater than 10; the organic solvent includes one or a mixture of isopropanol and ethanol; the basic solvent includes one or a mixture of ammonia water and sodium hydroxide solution; the volume ratio of the water to the silanizing reagent is 12:8; the stirring time is 11 - 13 hours, and the temperature is 20 - 30°C. In step S2, the organic basic solvent includes an organic solvent and a basic solvent, and the volume ratio of the organic solvent to the basic solvent is 75:2; the organic solvent includes one or a mixture of isopropanol and ethanol; the basic solvent includes one or a mixture of ammonia water and sodium hydroxide solution; and / or, the stirring time is 0.5 - 1.5 hours, and the temperature is 20 - 30°C; and / or, the drying temperature is 50 - 70°C.

[0012] In the present invention, after the prepared extraction material extracts selenoamino acids in health foods and is combined with LC-ICP-MS detection technology, it has a lower detection limit. Compared with the detection scheme of the standard NY / T 3870-2021 of the Ministry of Agriculture and Rural Affairs, the present invention reduces the detection limit by four orders of magnitude. Compared with the methods of Cao et al. (Cao, J., Cheng, Y., Xu, B. et al. Determination of Different Selenium Species in Selenium-Enriched Polysaccharide by HPLC-ICP-MS. Food Anal. Methods 2021, 14: 2420–2429.) and Lu Xin et al. (Lu Xin, Zhang Lin, Wang Tieliang, et al. Determination of Selenoamino Acids in Selenium-Enriched Wheat by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry [J]. Chinese Journal of Inorganic Analytical Chemistry, 2023, 13(12): 1466-1472.) using the same detection means, the detection limit of this method is reduced by 1-2 orders of magnitude compared with the above works. Compared with the works of Liang Yanqiu (Liang Qiuyan, Hua Zhenyu, Wang Huixin, et al. Determination of the Contents of Three Selenoamino Acids in Cuminum cyminum L. by Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry [J]. Journal of Food Safety and Quality, 2024, 15(19): 278-286.), Liu Yao (Liu Yao, Du Xingyuan, Zhang Chaoyang, et al. Determination of Selenoamino Acids in Selenoprotein by Microwave Hydrolysis-Liquid Chromatography-Atomic Fluorescence Spectrometry [J]. Chinese Journal of Inorganic Analytical Chemistry, 2022, 12(5): 98-104.) and others using liquid chromatography-tandem mass spectrometry and liquid chromatography-atomic fluorescence spectrometry as detection means, the method of the present invention also has a lower detection limit.

[0013] In a second aspect, in an optional embodiment of the present invention, a magnetic solid-phase extraction material is provided, which is prepared by the above preparation method.

[0014] In a third aspect, in an optional embodiment of the present invention, an application of the above magnetic solid-phase extraction material in the magnetic solid-phase extraction of selenoamino acids in health foods is provided.

[0015] In a fourth aspect, in an optional embodiment of the present invention, a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction is provided, including the following steps:

[0016] Mix the health food sample to be tested with the above magnetic solid-phase extraction material and vibrate for adsorption, so that the selenoamino acids in the health food sample to be tested are adsorbed onto the extraction material, then remove the upper liquid, and finally add an eluent to elute the extraction material, collect the eluent for liquid chromatography-inductively coupled plasma mass spectrometry detection; wherein, the pH value of the health food sample to be tested is 1-3.

[0017] In the present invention, if the health care sample to be tested is a solid, it is first dissolved in a solvent and then extracted.

[0018] Preferably, the volume-mass ratio of the health care sample to be tested and the extraction material is: 5 - 40 mL : 50 mg; and / or, the eluent is selected from one or a mixture of two of sodium phosphate solution or sodium hydroxide solution, the concentration of the sodium phosphate solution is 0.5 mol / L, and the concentration of the sodium hydroxide solution is 0.1 - 0.5 mol / L. The adsorption time is at least 5 min; and / or, the elution time is at least 5 min, and the volume of the eluent is at least 1 mL. The health care sample to be tested contains one or more of selenocysteine, selenomethionine, and methylselenocysteine.

[0019] Compared with the prior art, the present invention has one of the following beneficial effects:

[0020] 1. The magnetic solid-phase extraction material provided by the present invention has a good adsorption effect on selenoamino acids in health care products. The magnetic solid-phase extraction method can quickly separate the target selenoamino acids from the sample matrix, and has the characteristics of fast separation speed and simple operation.

[0021] 2. The present invention uses this extraction material for the extraction of selenoamino acids in health care products, and then combines it with LC-ICP-MS detection technology to establish a highly sensitive, simple, and stable extraction and detection method for selenoamino acids in health care products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is the SEM diagram of the magnetic solid-phase extraction material prepared in Example 1 of the present invention;

[0024] Figure 2 It is the adsorption efficiency diagram of the eluents obtained in Examples 2 - 6 and Comparative Examples 1 - 7 of the present invention for 3 selenoamino acids;

[0025] Figure 3 It is the adsorption efficiency diagram of the eluents obtained in Examples 2, 7 - 10 and Comparative Example 8 of the present invention for 3 selenoamino acids;

[0026] Figure 4 It is the schematic diagram of the results of LC-ICP-MS detection of the eluents obtained in Examples 11, 14 and Comparative Examples 11 - 16 of the present invention;

[0027] Figure 5 Schematic diagram of the results of LC-ICP-MS detection of the eluents obtained in Example 2, Examples 11-13 and Comparative Examples 9-10 of the present invention;

[0028] Figure 6 Schematic diagram of the results of LC-ICP-MS detection of the eluents obtained in Comparative Example 18 and Comparative Example 20 of the present invention;

[0029] Figure 7 Schematic diagram of the results of LC-ICP-MS detection of the eluents obtained in Example 2, Example 16, Example 18, Comparative Example 22 and Comparative Example 24 of the present invention. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] In the following examples and comparative examples, the target selenoamino acids are: selenocystine (SeCys2), selenomethionine (SeMet), methylselenocysteine (MeSeCys). The standard stock solution of selenocystine (1 mg / mL, calculated as Se) was prepared by dissolving selenocystine in 0.1 mol / L HCl. The standard stock solutions of selenomethionine and methylselenocysteine (1 mg / mL, calculated as Se) were respectively dissolved by selenomethionine and methylselenocysteine in ultrapure water (18.2 MΩ·cm). The working solutions were obtained by diluting the standard stock solutions with ultrapure water to appropriate concentrations. A blank solution with pH = 1.5 was prepared using nitric acid.

[0032] All chemicals and reagents used were at least of analytical reagent grade. Ferric chloride hexahydrate (FeCl3·6H2O), ferrous chloride tetrahydrate (FeCl2·4H2O), ammonia water (NH3·H2O), isopropanol, formic acid, sodium hydroxide (NaOH) and N,N-dimethylformamide (DMF) were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Zirconium oxychloride octahydrate (ZrOCl2·8H2O), sodium 2-sulfoterephthalate monosodium salt, tetraethoxysilane (TEOS) were purchased from Aladdin Reagent Co., Ltd. High-purity deionized water obtained using a Milli-Q system was used throughout the work. HPLC-grade methanol (MeOH) was purchased from Sigma-Aldrich.

[0033] A liquid chromatography (LC) system (Agilent, USA) and C 18The target compounds were separated and detected using an LC column (250×4.6 mm, 5 μm). The target selenium - containing amino acids were detected by connecting a liquid chromatography system to an inductively coupled plasma mass spectrometer 7800 (Agilent, USA). The relevant instrument operating parameters are listed in Table 1.

[0034] Table 1 LC - ICP - MS detection parameters

[0035]

[0036] Health food samples were purchased from Enshi area, Hubei Province, including 2 selenium - rich liquid health foods. The samples were directly diluted with ultrapure water and then subjected to MSPE and LC - ICP - MS detection.

[0037] The selenium - containing amino acids in liquid health food sample 1 were 290 μg / L SeCys2 and 1.88 μg / L SeMet. The selenium - containing amino acids in liquid health food sample 2 were 119 μg / L SeCys2, 7.24 μg / L MeSeCys and 7.89 μg / L SeMet.

[0038] Example 1

[0039] This example provides a method for preparing a magnetic solid - phase extraction material, which includes the following steps:

[0040] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O and dissolve them in 200 mL of deionized water protected by high - purity nitrogen. Stir at 85 °C for 30 minutes. Then add 40 mL of 30% concentrated ammonia water and stir gently to generate Fe3O4 nanoparticles, and wash with deionized water.

[0041] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL) and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol to obtain SiO2 / Fe3O4 particles.

[0042] S3: Take 1.0 g of ZrOCl2·8H2O and 0.83 g of sodium 2 - sulfoterephthalate monosodium salt and disperse them in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reaction kettle and react at 150 °C for 24 hours. After cooling to room temperature, take it out and wash 3 times with 20 mL of DMF to obtain Uio - 66 - SO3H particles.

[0043] S4: Take 2.0 g of SiO2 / Fe3O4 and 2.0 g of Uio-66-SO3H and disperse them in a mixture of isopropanol (150 mL) and concentrated ammonia water (4 mL). Then add 1 mL of TEOS and stir at room temperature for 1 hour to prepare SiO2 / Fe3O4&Uio-66-SO3H. Wash it 3 times with 50 mL of ethanol and vacuum dry it at 60 °C to obtain the magnetic solid phase extraction material.

[0044] The magnetic solid phase extraction material prepared in Example 1 was characterized by scanning electron microscopy, and the SEM image results are shown in Figure 1 。

[0045] Example 2

[0046] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0047] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0048] Example 3

[0049] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0050] Transfer 30 mL of the health food sample to be tested (pH value is 1) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0051] Example 4

[0052] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0053] Transfer 30 mL of the health care sample to be tested (pH value is 2) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0054] Example 5

[0055] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0056] Transfer 30 mL of the health care sample to be tested (pH value is 2.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0057] Example 6

[0058] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0059] Transfer 30 mL of the health care sample to be tested (pH value is 3) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0060] Example 7

[0061] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0062] Transfer 5 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0063] Example 8

[0064] This example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared in Example 1, which includes the following steps:

[0065] Transfer 10 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0066] Example 9

[0067] This example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared in Example 1, which includes the following steps:

[0068] Transfer 20 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0069] Example 10

[0070] This example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared in Example 1, which includes the following steps:

[0071] Transfer 40 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0072] Example 11

[0073] This example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared in Example 1, which includes the following steps:

[0074] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.1 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0075] Example 12

[0076] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0077] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.15 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0078] Example 13

[0079] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0080] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0081] Example 14

[0082] This example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared in Example 1, including the following steps:

[0083] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L sodium phosphate solution, shake for elution for 10 min, and filter to obtain the eluate.

[0084] Example 15

[0085] This embodiment provides a method for preparing a magnetic solid-phase extraction material, comprising the following steps:

[0086] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O and dissolve them in 200 mL of deionized water protected by high-purity nitrogen. Stir at 85 °C for 30 minutes. Then add 40 mL of concentrated ammonia water with a volume fraction of 30%, and gently stir to generate Fe3O4 nanoparticles, and wash with deionized water.

[0087] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL), and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol to obtain SiO2 / Fe3O4 particles.

[0088] S3: Take 1.0 g of ZrOCl2·8H2O and 0.83 g of monosodium 2-sulfoterephthalate and disperse them in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reaction kettle and react at 150 °C for 24 hours. After cooling to room temperature, take it out and wash 3 times with 20 mL of DMF to obtain Uio-66-SO3H particles.

[0089] S4: Take 2.0 g of SiO2 / Fe3O4 and 2.5 g of Uio-66-SO3H and disperse them in a mixture of isopropanol (150 mL) and concentrated ammonia water (4 mL), and then add 1 mL of TEOS. Stir at room temperature for 1 hour to prepare SiO2 / Fe3O4&Uio-66-SO3H, wash 3 times with 50 mL of ethanol, and vacuum dry at 60 °C to obtain the magnetic solid-phase extraction material.

[0090] Example 16

[0091] This embodiment provides a method for extracting selenoamino acids in health foods by the magnetic solid-phase extraction method using the magnetic solid-phase extraction material prepared in Example 15, comprising the following steps:

[0092] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0093] Example 17

[0094] This embodiment provides a method for preparing a magnetic solid-phase extraction material, comprising the following steps:

[0095] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O and dissolve them in 200 mL of deionized water protected by high-purity nitrogen. Stir at 85 °C for 30 minutes. Then add 40 mL of 30% concentrated ammonia water and gently stir to generate Fe3O4 nanoparticles, and wash with deionized water.

[0096] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL), and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol to obtain SiO2 / Fe3O4 particles.

[0097] S3: Take 1.0 g of ZrOCl2·8H2O and 0.83 g of sodium 2-sulfoterephthalate monosodium salt and disperse them in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reaction kettle and react at 150 °C for 24 hours. After cooling to room temperature, take it out and wash 3 times with 20 mL of DMF to obtain Uio-66-SO3H particles.

[0098] S4: Take 2.0 g of SiO2 / Fe3O4 and 3.0 g of Uio-66-SO3H and disperse them in a mixture of isopropanol (150 mL) and concentrated ammonia water (4 mL), and then add 1 mL of TEOS. Stir at room temperature for 1 hour to prepare SiO2 / Fe3O4&Uio-66-SO3H. Wash 3 times with 50 mL of ethanol, and after vacuum drying at 60 °C, obtain the magnetic solid-phase extraction material.

[0099] Example 18

[0100] This embodiment provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared in Example 17, comprising the following steps:

[0101] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0102] Comparative Example 1

[0103] This comparative example provides a method for extracting selenoamino acids from health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0104] Transfer 30 mL of the health food sample to be tested (pH value is 4) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0105] Comparative Example 2

[0106] This comparative example provides a method for extracting selenoamino acids from health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0107] Transfer 30 mL of the health food sample to be tested (pH value is 5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0108] Comparative Example 3

[0109] This comparative example provides a method for extracting selenoamino acids from health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0110] Transfer 30 mL of the health food sample to be tested (pH value is 6) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0111] Comparative Example 4

[0112] This comparative example provides a method for extracting selenoamino acids from health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0113] Transfer 30 mL of the health care sample to be tested (pH value is 7) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0114] Comparative Example 5

[0115] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0116] Transfer 30 mL of the health care sample to be tested (pH value is 8) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0117] Comparative Example 6

[0118] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0119] Transfer 30 mL of the health care sample to be tested (pH value is 9) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0120] Comparative Example 7

[0121] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0122] Transfer 30 mL of the health care sample to be tested (pH value is 10) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake for elution for 10 min, and filter to obtain the eluate.

[0123] Comparative Example 8

[0124] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0125] Transfer 50 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0126] Comparative Example 9

[0127] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0128] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.02 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0129] Comparative Example 10

[0130] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0131] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, shake and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.05 mol / L NaOH solution, shake and elute for 10 min, and then filter to obtain the eluate.

[0132] Comparative Example 11

[0133] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0134] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.1 mol / L ammonia water solution, shake for elution for 10 min, and filter to obtain the eluate.

[0135] Comparative Example 12

[0136] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0137] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L sodium carbonate solution, shake for elution for 10 min, and filter to obtain the eluate.

[0138] Comparative Example 13

[0139] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0140] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L sodium sulfate solution, shake for elution for 10 min, and filter to obtain the eluate.

[0141] Comparative Example 14

[0142] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid phase extraction using the magnetic solid phase extraction material prepared based on Example 1, including the following steps:

[0143] Transfer 30 mL of the health care sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid phase extraction material into a 50 mL centrifuge tube, shake for adsorption for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L sodium citrate solution, shake for elution for 10 min, and filter to obtain the eluate.

[0144] Comparative Example 15

[0145] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0146] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.5 mol / L sodium acetate solution, vibrate and elute for 10 min, and then filter to obtain the eluate.

[0147] Comparative Example 16

[0148] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Example 1, including the following steps:

[0149] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 1 mol / L nitric acid solution, vibrate and elute for 10 min, and then filter to obtain the eluate.

[0150] Comparative Example 17

[0151] This comparative example provides a method for preparing a magnetic solid-phase extraction material, including the following steps:

[0152] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O, dissolve them in 200 mL of deionized water protected by high-purity nitrogen, and stir at 85 °C for 30 minutes. Then add 40 mL of 30% concentrated ammonia water, gently stir to generate Fe3O4 nanoparticles, and wash with deionized water.

[0153] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL), and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol, and vacuum dry at 60 °C to obtain the SiO2 / Fe3O4 magnetic solid-phase extraction material.

[0154] Comparative Example 18

[0155] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Comparative Example 17, including the following steps:

[0156] Transfer 12 portions of 30 mL of the health food sample to be tested (pH values are 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10) and 50 mg of the SiO2 / Fe3O4 magnetic solid-phase extraction material into 50 mL centrifuge tubes, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube, and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and then filter to obtain the eluate.

[0157] Comparative Example 19

[0158] Take 1.0 g of ZrOCl2·8H2O and 0.83 g of sodium 2-sulfoterephthalate and disperse them in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reaction kettle and react at 150 °C for 24 hours. After cooling to room temperature, take it out, wash it 3 times with 20 mL of DMF, and vacuum dry at 60 °C to obtain the Uio-66-SO3H extraction material.

[0159] Comparative Example 20

[0160] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the extraction material prepared based on Comparative Example 19, including the following steps:

[0161] Transfer 12 portions of 30 mL of the health food sample to be tested (pH values are 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10) and 50 mg of the Uio-66-SO3H extraction material into 50 mL centrifuge tubes, vibrate and adsorb for 10 min, and then centrifuge to separate the solid material and the liquid material. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution to the solid material, vibrate and elute for 10 min, and then filter to obtain the eluate.

[0162] Comparative Example 21

[0163] This comparative example provides a method for preparing a magnetic solid-phase extraction material, including the following steps:

[0164] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O and dissolve them in 200 mL of deionized water protected by high-purity nitrogen. Stir at 85 °C for 30 minutes. Then add 40 mL of 30% concentrated ammonia water and gently stir to generate Fe3O4 nanoparticles, and wash with deionized water.

[0165] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL), and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol to obtain SiO2 / Fe3O4 particles.

[0166] S3: Take 1.0 g of ZrOCl2·8H2O and 0.83 g of sodium 2-sulfoterephthalate monosodium salt and disperse them in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reactor and react at 150 °C for 24 hours. After cooling to room temperature, take it out and wash 3 times with 20 mL of DMF to obtain Uio-66-SO3H particles.

[0167] S4: Take 2.0 g of SiO2 / Fe3O4 and 1.8 g of Uio-66-SO3H and disperse them in a mixture of isopropanol (150 mL) and concentrated ammonia water (4 mL), and then add 1 mL of TEOS. Stir at room temperature for 1 hour to prepare SiO2 / Fe3O4&Uio-66-SO3H. Wash 3 times with 50 mL of ethanol, and after vacuum drying at 60 °C, obtain the magnetic solid-phase extraction material.

[0168] Comparative Example 22

[0169] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Comparative Example 21, including the following steps:

[0170] Transfer 30 mL of the health food sample to be measured (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material to a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0171] Comparative Example 23

[0172] This comparative example provides a method for preparing a magnetic solid-phase extraction material, including the following steps:

[0173] S1: First, weigh 11.68 g of FeCl3·6H2O and 4.30 g of FeCl2·4H2O and dissolve them in 200 mL of deionized water protected by high-purity nitrogen. Stir at 85 °C for 30 minutes. Then add 40 mL of 30% concentrated ammonia water, gently stir to generate Fe3O4 nanoparticles, and wash with deionized water.

[0174] S2: Disperse 4.0 g of the prepared Fe3O4 nanoparticles in a mixture of isopropanol (100 mL), deionized water (12 mL), and concentrated ammonia water (7 mL), and then add 8 mL of tetraethyl orthosilicate (TEOS) to prepare SiO2 / Fe3O4. Stir at room temperature for 12 hours, wash 3 times with 200 mL of deionized water and 3 times with 50 mL of ethanol to obtain SiO2 / Fe3O4 particles.

[0175] S3: Disperse 1.0 g of ZrOCl2·8H2O and 0.83 g of sodium 2-sulfoterephthalate monosodium salt in DMF (20 mL), add 11.7 mL of formic acid, and ultrasonically disperse for 30 minutes. Place this mixture in a 100 mL hydrothermal reaction kettle and react at 150 °C for 24 hours. After cooling to room temperature, take it out and wash 3 times with 20 mL of DMF to obtain Uio-66-SO3H particles.

[0176] S4: Disperse 2.0 g of SiO2 / Fe3O4 and 3.2 g of Uio-66-SO3H in a mixture of isopropanol (150 mL) and concentrated ammonia water (4 mL), and then add 1 mL of TEOS. Stir at room temperature for 1 hour to prepare SiO2 / Fe3O4&Uio-66-SO3H. Wash 3 times with 50 mL of ethanol, and after vacuum drying at 60 °C, obtain the magnetic solid-phase extraction material.

[0177] Comparative Example 24

[0178] This comparative example provides a method for extracting selenoamino acids in health foods by magnetic solid-phase extraction using the magnetic solid-phase extraction material prepared based on Comparative Example 23, including the following steps:

[0179] Transfer 30 mL of the health food sample to be tested (pH value is 1.5) and 50 mg of the magnetic solid-phase extraction material into a 50 mL centrifuge tube, vibrate and adsorb for 10 min, then use a Nd-Fe-B strong magnet to attract the magnetic particles at the bottom of the centrifuge tube and remove the upper liquid. Subsequently, add 1.0 mL of 0.2 mol / L NaOH solution, vibrate and elute for 10 min, and filter to obtain the eluate.

[0180] Experimental Example

[0181] The eluates obtained from Examples 2-6 and Comparative Examples 1-7 were detected by LC-ICP-MS, and then the adsorption efficiency was statistically analyzed. The results are shown in Figure 2 , and it can be seen from Figure 2 that the adsorption efficiency of the three selenoamino acids can remain above 90% when the sample pH is between 1 and 3, and then gradually decreases as the sample pH increases.

[0182] The eluates obtained from Examples 2, 7-10 and Comparative Example 8 were detected by LC-ICP-MS, and then the adsorption efficiency was statistically analyzed. The results are shown in Figure 3 , and it can be seen from Figure 3 that in the 5-40 mL health care samples to be tested, the extraction efficiency of the three selenoamino acids remains unchanged, while when it exceeds 40 mL, the extraction efficiency of the three selenoamino acids decreases significantly.

[0183] The eluates obtained from Examples 11, 14 and Comparative Examples 11-16 were detected by LC-ICP-MS. The results are shown in Figure 4 , where A is Comparative Example 11, B is Comparative Example 12, C is Example 14, D is Example 11, E is Comparative Example 13, F is Comparative Example 14, G is Comparative Example 15, and H is Comparative Example 16. It can be seen from Figure 4 that the elution effects of the eluates of Example 11 and Example 14 are significantly better than those of the eluates of Comparative Examples 11-16.

[0184] The eluates obtained from Examples 2, 11-13 and Comparative Examples 9-10 were detected by LC-ICP-MS. The results are shown in Figure 5 , and it can be seen from Figure 5 that the elution efficiency of the three selenoamino acids gradually increases as the sodium hydroxide concentration increases and basically remains unchanged after reaching 0.15 mol / L.

[0185] The eluate obtained from Example 2 was introduced into LC-ICP-MS for quantitative analysis. The results are shown in Table 2.

[0186] Table 2 Analytical performance of the MSPE-LC-ICP-MS detection method

[0187]

[0188] a c = 0.20 μg / L.

[0189] The detection limit of Example 2 (the concentration of the analyte corresponding to three times the standard deviation of the blank signal) was 8.37 - 18.4 ng / L, and the relative standard deviation was 5.28% - 12.4%; in the linear range of 0.05 - 50 μg / L, the r value was 0.9951 - 0.9973; the enrichment factor (the slope ratio of the calibration curves before and after MSPE) was 27.2 - 28.1.

[0190] To verify the applicability of the method of the present invention for analyzing three selenoamino acids in actual samples, it was applied to determine the contents of three selenoamino acids in liquid health products. The results and recoveries of the actual samples and spiked samples are listed in Table 3.

[0191] Table 3 Analysis results and spiked recovery results of health food samples (mean±s.d., n = 3)

[0192]

[0193] a: The liquid health food sample was diluted 50 times.

[0194] As shown in the table, SeCys2 and SeMet among the three selenoamino acids were detected in both of the two liquid health products, while MeSeCys was only detected in one liquid health product, and the content of SeCys2 was the highest in the two liquid health products. The accuracy of the method was verified by a spiked recovery experiment, and the recoveries of SeCys2, MeSeCys and SeMet were 83.9 - 108%.

[0195] The above results indicate that this method is applicable to the detection of target selenoamino acids in health foods, and has good accuracy while having high sensitivity.

[0196] The eluents obtained from Comparative Example 18 and Comparative Example 20 were detected by LC-ICP-MS, and the results are as Figure 6 shown, Figure 6 The results in show that: the adsorption efficiency of the eluents at different pHs in Comparative Example 18 for selenoamino acids was all lower than 50%, and quantitative adsorption of selenoamino acids could not be achieved; the adsorption efficiency of the eluents at different pHs in Comparative Example 20 for selenoamino acids was all lower than 10%, which was mainly because the Uio-66-SO3H extraction material did not contain a magnetic core, and a strong magnet could not separate the extraction material from the sample solution / eluent, so quantitative adsorption of selenoamino acids could not be achieved.

[0197] The eluents obtained from Example 2, Example 16, Example 18, Comparative Example 22 and Comparative Example 24 were detected by LC-ICP-MS, and the results are as Figure 7 shown, Figure 7The results show that the extraction efficiencies of the three seleno - amino acids in Example 2, Example 16, and Example 18 can all be maintained above 80%, enabling the quantitative extraction of seleno - amino acids. However, the extraction efficiencies of the three seleno - amino acids in Comparative Example 22 and Comparative Example 24 are lower than 80%, and quantitative extraction cannot be achieved. This is mainly because when the proportion of Uio - 66 - SO3H is too low, the adsorption efficiency of seleno - amino acids is insufficient, and when the proportion of Uio - 66 - SO3H is too high, efficient and rapid separation of the magnetic extraction material and the liquid cannot be achieved. Therefore, the extraction efficiency will decrease in both cases.

[0198] Although the principle of the present invention has been described in detail above in combination with the preferred embodiments of the present invention, those skilled in the art should understand that the above - mentioned embodiments are only explanations of the illustrative implementation modes of the present invention, and do not limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for preparing a magnetic solid phase extraction material, characterized in that: The following steps are involved: S1: dispersing Fe3O4 nanoparticles in an organic alkaline solvent, adding a silanization agent, stirring and washing to obtain Fe3O4 / SiO2 particles; S2: Dispersing the Fe3O4 / SiO2 particles and Uio-66-SO3H particles in an organic alkaline solvent, adding a silanization agent, stirring, washing and drying to obtain a magnetic solid phase extraction material.

2. The method for preparing a magnetic solid phase extraction material according to claim 1, characterized in that: The mass ratio of the Fe3O4 / SiO2 particles to the Uio-66-SO3H particles is 1:1-1.5; and / or, The mass volume ratio of the Fe3O4 nanoparticles and the silanization agent is 1g:2mL; and / or, The silanization agent includes tetramethoxysilane or tetraethoxysilane or a mixture of the two.

3. The method for preparing a magnetic solid phase extraction material according to claim 1, characterized in that: In step S1, the organic alkaline solvent includes an organic solvent, water and an alkaline solvent, and the volume ratio of the organic solvent, water and ammonia water is 100:12:7; The pH of the organic alkaline solvent is greater than 10; The organic solvent includes one of isopropanol and ethanol or a mixture of the two; The alkaline solvent includes one of aqueous ammonia and sodium hydroxide solution or a mixture of the two; The volume ratio of water to silanization agent is 12:8; The stirring time is 11-13 hours, and the temperature is 20-30°C.

4. The method for preparing a magnetic solid phase extraction material according to claim 1, characterized in that: In step S2, the organic alkaline solvent includes an organic solvent and an alkaline solvent, and the volume ratio of the organic solvent to the alkaline solvent is 75:2; The organic solvent includes one of isopropanol and ethanol or a mixture of the two; The alkaline solvent includes one of aqueous ammonia and sodium hydroxide solution or a mixture of the two; The stirring time is 0.5-1.5 hours and the temperature is 20-30° C.; and / or, The drying temperature is 50-70°C.

5. A magnetic solid phase extraction material, characterized in that: The preparation method is adopted according to any one of claims 1 to 4.

6. Use of the magnetic solid phase extraction material according to claim 5 in extracting selenoamino acids from health foods using a magnetic solid phase extraction method.

7. A method for extracting selenoamino acids from health food using magnetic solid phase extraction, characterized in that: The following steps are involved: The health sample to be tested and the magnetic solid phase extraction material according to claim 5 are mixed and then vibrated and adsorbed, so that the selenoamino acid in the health sample to be tested is adsorbed on the extraction material, and then the upper liquid is removed, and finally an eluent is added to elute the extraction material, and the eluent is collected for liquid chromatography-inductively coupled plasma mass spectrometry detection; Wherein, the pH value of the health care sample to be tested is 1-3.

8. The method for extracting selenoamino acids from health food using magnetic solid phase extraction according to claim 7, characterized in that: The volume mass ratio of the health sample to be tested and the extraction material is: 5-40mL:50mg; and / or, The eluent is selected from sodium phosphate solution or sodium hydroxide solution or a mixture of the two. The concentration of the sodium phosphate solution is 0.5 mol / L, and the concentration of the sodium hydroxide solution is 0.1-0.5 mol / L.

9. The method for extracting selenoamino acids from health food using magnetic solid phase extraction according to claim 7, characterized in that: The adsorption time is at least 5 minutes; and / or, The elution time is at least 5 min, and the volume of the eluent is at least 1 mL.

10. The method for extracting selenoamino acids from health food using magnetic solid phase extraction according to claim 7, characterized in that: The health sample to be tested contains one or more of selenocysteine, selenomethionine and methylselenocysteine.

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